Re: Join Logical File Problem.

[Buck Calabro/commsoft<mcalabro@xxxxxxxxxxxx>]

-snip-

>For the problem of building access path dynamically 
>which takes long time, for that I am trying to 
>replace LF   over  OPNQRYF.

-snip-

>Mr. David Duerr has suggested a solution by using 
>SQL VIEW.  I am going to try that today.

Perhaps if you build appropriate logicals over your
PF's you can cut down on the time to process the
OPNQRYF.  As David suggested, if OPNQRYF can find
an access path to help optimise the query, it will
use it.  The logicals do not need to be JOINs in order
to speed things up, but they should be over your
fields that you use in your selection and kfld
parameters.

This topic is a difficult one to deal with because
there are very many variables that make each situation
unique.  For some pointers on optimising query/SQL/
OPNQRYF (which all use the same engine, I believe)
see the IBM manual DB2 for AS400 SQL Programming.
For V4R3, chapter 22 contains information on the
query optimiser and how to improve performance.

Buck Calabro
CommSoft, Albany, NY
mailto:mcalabro@commsoft.net




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